wc -l medals.txt
grep -E "中国|中国香港|中国台北" medals.txt | sort -k2,2nr -k3,3nr -k4,4nr
sort -t, -k4,4nr medals.txt | head -n 5 | cut -d, -f1
sort -t, -k2,2nr medals.txt | head -n 5 | awk -F, {sum += } END {print sum}
